The present invention generally relates to a magnetic recording and reproducing apparatus such as a video tape recorder or the like, and more particularly, to a magnetic recording and reproducing apparatus of a helical scan system capable of readily realizing special reproducing functions through reduction of a tape travelling load.
FIGS. 2(a) and 2(b) show one example of a conventional magnetic recording and reproducing apparatus. A magnetic tape 44 is accommodated in a tape cassette 41 and passed around a supply reel 42 and take-up reel 43 disposed to contact the same plane within the tape cassette 41. The magnetic tape 44 is drawn out by a set of loading apparatus 58 and 59 from tape storing portions 60 and 61 of the tape cassette 41 causing the magnetic tape to contact part of the outer peripheral surface of a rotary head cylinder 50 generally in an M-shape as shown. The loading apparatus 58 and 59, respectively, include a first guide roller 48 and a first inclining post 49, and a second inclining post 51 and a second guide roller 52. The first and second inclining posts 49 and 51 are respectively disposed unrotatably in the vicinity of the rotary head cylinder 50 in an inclined state, while each of the first and second guide rollers 48 and 52 is adapted to be rotatable.
The magnetic tape 44 directed around the outer peripheral surface of the rotary head cylinder 50 is held between a capstan 56 and a pinch roller 57 so as to be driven for running.
Subsequently, the states of travelling or running of the magnetic tape 44 in the above known arrangement will be described.
The magnetic tape 44 is paid out from the supply reel 42 in a direction parallel to that of the plane to which said reels 42 and 43 contact. Therefore is twisted by the first inclining post 49 so as to be inclined in its tape travelling reference face (which is a face perpendicular to an axis of a post guiding a tape), after having been guided by a tension post 45, a rotary roller 46, an erasing head 47 and the first guide roller 48, and is helically wound around the outer peripheral surface of the rotary head cylinder 50.
The magnetic tape 44 leaving the rotary head 50 is guided by the second guide roller 52, a rotary roller 53, an audio head 54 and a fixed guide 55, after again having been twisted by the second inclining post 51 so as to be corrected in the inclination of its tape travelling reference face. Thereafter, the magnetic tape 44 is fed into the tape cassette 41 through a capstan 56 and a pinch roller 57, and wound onto the take-up reel 43.
It is to be noted here that the travelling system of the magnetic tape according to the arrangement as described so far is generally called an M loading type travelling system.
Generally, in the case where a post is vertically mounted with respect to a mounting surface (referred to as a vertical post hereinafter), adjustments may be made more easily than in the case where a post is mounted at an incline on the mounting surface by a predetermined degree (referred to as an inclining post hereinafter). Moreover, with a vertical post, it is possible to provide flanges for controlling or restricting tape running through employment of a rotatable construction, whereas in the inclining post, such flanges as in the rotatable construction can not be provided, and thus, the inclining post is disadvantageous as compared with the vertical post also from the viewpoint of tape running control.
Nevertheless, conventional magnetic recording and reproducing apparatus are arranged so that the first and second inclining posts 49 and 51 are respectively disposed in the vicinity of the inlet and output portions of the rotary head 50. These posts require the highest accuracy in the tape running system. Thus, extremely high processing accuracy is also required for the processing of these parts and considerable time and labor are necessary for the assembling and adjustments of the apparatus.
Furthermore, due to the fact that a large tape winding angle is necessary with respect to the first and second inclining posts 49 and 51, the tape travelling load is undesirably increased making it difficult to rapidly feed the magnetic tape with said tape wound around the outer peripheral surface of the rotary head 50 from the viewpoints of damage to the tape and large power consumption.